I noticed when I jumped on my rm 250 the other day for long trail ride (not gettin on it much) it was very snappy for awhile, then after putting around it didnt seem as if it was hitting the powerband nearly as hard. Is there a powervalve that opens up at a certain rpm or something that could get stuck? Seemed like once ran through the gears, and brought the revs back down it didnt have much bottom end and never really hit the powerband hard. Could this be from a fouling spark plug, or something different? Thanks!